In pressure spray washers and the like it is necessary to introduce one or more fluids into the flow of another fluid. For example, a liquid soap or other cleaning agent is mixed with air and then introduced into a water flow to create a foaming mixture. Generally, the soap or other cleaning agent is drawn from a small tank which is attached or internal to the pressure washer. Because the tank is small, a cleaning operation may need to be frequently interrupted to refill the tank.
Berfield, U.S. Pat. No. 5,230,368, discloses a chemical intake system for a pressure washer which controls the amount of soap delivered into a water stream. The soap is first added to a tank which fits over the spray nozzle and which is retained against the pressure washer. A first tube interconnects the venturi with the soap in the tank. A second tube is connected between the venturi and one of a plurality of apertures in communication with an air space above the soap in the tank. Each aperture has a different diameter which permits a different amount of air flow through the second tube so that the amount of soap flowing through the suction tube into the water stream can be controlled.
Rogers, U.S. Pat. No. 3,853,784, discloses a foam forming apparatus wherein chemical is drawn from an external container, such as a bucket, and combined with water flow in a venturi. Compressed air is added to an outlet chamber and mixed with the water and chemical to generate foam through a spray nozzle.
Neither of the above systems is entirely satisfactory. While the washer disclosed in the Berfield '368 patent allows the user to control the amount of chemical introduced into the water stream, the tank attached to the pressure washer unit has a relatively small capacity that may need to be frequently refilled during long washing applications. Further, the tank must be emptied and refilled whenever it is desired to change the cleaning agent. The apparatus disclosed in the Rogers '784 patent can only be operated with a separate external chemical container, which detracts from the convenience of a self-contained unit. Thus, there remains a need for a chemical intake system for a pressure washer which allows the user to easily refill and change cleaning agents which are combined with the water flowing out the spray nozzle.